Search Results (23)

Shield tunnel construction inevitably disturbs existing upper buildings. This paper takes the section from Zhongyi Road Station to Housihu Fourth Road Station of Wuhan Metro Line 12 as the engineering background, where twin shield tunnels pass beneath Zizhu Kindergarten. Based on field monitoring data, this paper systematically analyzes the development laws of surface settlement and building settlement. Numerical simulation is adopted and compared with measured data to verify the reliability of the model. With the validated numerical model, this paper investigates the influencing factors of building settlement. The results show that the maximum ground surface settlement during shield construction is approximately 6.84 mm, and the maximum building settlement is about 4.63 mm. The horizontal relative position between piles and tunnels changes the superposition mode of ground settlement troughs. Building settlement reaches the minimum when twin tunnels pass beneath symmetrically. Eccentric crossing aggravates building settlement to a certain extent. The maximum building settlement increases with the rise of tunnel buried depth. The research results can provide a reference for deformation control and construction optimization of similar twin shield tunnels crossing beneath buildings with piled-raft foundations. Full article

Tunnelling-induced safety risks from adjacent piles have become increasingly severe with the rapid development of urban underground space. Model tests have become essential for revealing the complex pile-tunnel interaction mechanism. This paper reviews the research progress of model tests on the influence of single-line tunnelling on adjacent piles, focusing on test soil materials, tunnel simulation methodologies, analysis of test results, and research prospects. However, current model test studies are constrained by several critical limitations, including insufficient similarity between soil materials and prototype conditions, and overly idealized simulation of tunnel excavation. This paper identifies a significant research gap: the inability of current volume-loss techniques to capture 3D dynamic factors (e.g., face pressure and grouting timing) and the lack of meso-scale observation at the pile-soil interface. This review provides a systematic synthesis of these methodological challenges and proposes future research prospects to provide a more scientific basis for engineering design and risk control. Full article

To evaluate the coupled deformation of existing shield tunnels induced by multi-segment excavations with isolation piles, this study develops an integrated analytical framework combining a Kerr three-parameter foundation-plate model with a three-dimensional image-source solution. A closed-form expression for the soil displacement field is first derived by incorporating layered soil conditions, staged excavation, and associated spatial effects. The soil–pile interaction of isolation piles is then modeled using the Kerr foundation, and the flexural response is obtained through variational formulation and finite-difference discretization. These responses are sequentially propagated through the excavation stages, enabling the superposition of multi-pit effects on the final retaining-wall deformation. The image-source method and a volume-equivalent transformation are further used to convert wall deformation into an additional stress field acting on the tunnel, which is ultimately coupled with a tunnel–soil deformation–coordination model to compute horizontal tunnel displacements. This unified workflow establishes a continuous mechanical transfer chain—from excavation-induced soil loss to isolation-pile bending and finally tunnel deformation. Parametric analyses show that lateral displacement of the retaining structure is jointly governed by wall bending and pit-bottom uplift, producing a right-skewed “S-shaped” profile. The bending-moment peak shifts toward earlier-excavated zones, indicating a memory effect of excavation sequencing. Two engineering cases verify that the proposed method accurately reproduces the magnitude and depth of measured wall deflections, while predicted tunnel displacements show a near-Gaussian pattern with high accuracy near the peak. The analytical framework provides a robust theoretical basis for optimizing pit segmentation and excavation sequencing adjacent to shield tunnels. Full article

Underground metro tunnel failures in recent years have caused significant economic losses and posed serious risks to surface structures, highlighting the importance of accurately predicting tunnelling-induced ground deformations. Surface settlements occurring during TBM excavation may adversely affect existing infrastructure, particularly in sensitive urban areas. This study evaluates surface deformations induced by a TBM-driven metro tunnel as a case study, explicitly considering tunnel–structure interaction at locations where piled bridge piers are present. Due to site sensitivity, topographic monitoring was conducted during TBM passage, and measured settlement data were used for assessment. Settlement analyses were performed using the Peck (1969) empirical method and finite element modelling in Plaxis. Two constitutive soil models, Mohr–Coulomb (MC) and Hardening Soil (HS), were adopted to compare their predictive performance. The results show that the MC model predicts the highest surface settlements, whereas the Peck (1969) method provides results close to those obtained with the HS model, despite not explicitly incorporating structural loads. From the finite element tunnel models, it was determined—particularly from the two coordinate routes—that the HS model achieved prediction accuracy of up to approximately 95% compared to the measured values. Overall, the Peck approach and the HS model yielded more consistent predictions than the MC model for the investigated conditions, emphasizing the importance of appropriate soil model selection in finite element analyses of tunnelling-induced settlements. Full article

This study examines the influence of adjacent tunnel excavation on pile-supported embankment in soft clay under both unconsolidated and long-term consolidated conditions. A comprehensive three-dimensional numerical model was developed to simulate the coupled hydro-mechanical interaction between the embankment, piles, and surrounding ground. The soft clay behaviour was described using a hypoplastic constitutive model enhanced with intergranular strain theory to capture stress-dependent stiffness, dilatancy, and degradation under loading. Three tunnel alignments relative to the pile foundation alongside the pile shaft (S), near the pile toe (T), and beneath the pile toe (B) were analyzed to evaluate deformation and load transfer mechanisms. Results indicate that tunnelling induces significant differential settlements, with maximum values of 0.49%, 0.20%, and 0.45% for Cases S, T, and B, respectively. Consolidation substantially reduced both surface and pile settlements while improving subgrade stiffness and load-carrying performance. The maximum bending moment in the leading pile reached 142 kNm at Z/Lp = 0.56 under unconsolidated conditions and decreased following consolidation. The findings highlight the critical role of tunnel depth and consolidation state in controlling deformation, stress redistribution, and structural safety of pile-supported embankment during tunnelling activities. Full article

In recent years, the increasing complexity of shield tunneling environments has made it critical to control the deformation of adjacent excavation structures and surrounding soils. This study employs numerical simulation using MIDAS GTS/NX to comprehensively analyze the spatial interaction factors between shield tunnels and wall-pile-anchor-supported foundation pits. Structural parameters of the retaining system and tunneling conditions are also evaluated to identify the key factors influencing construction-induced deformation. The results show that the maximum settlement of the adjacent retaining wall occurs when the tunnel burial depth reaches 1.4L, where L is the height of the diaphragm wall. In addition, when the horizontal distance between the tunnel and the excavation is less than 0.75D (D being the tunnel diameter), significant settlement deformation is observed in the nearby support structures. A linear correlation is also identified between the variation in tunnel crown settlement and the excavation depth of the overlying pit during tunnel undercrossing. Furthermore, sensitivity analysis indicates that increasing the embedment depth of the diaphragm wall effectively reduces horizontal displacement at the wall base. Increasing the wall thickness decreases displacement in the upper section of the wall. Similarly, increasing pile diameter and anchor length and diameter, while reducing the inclination angle of anchors, are all effective in minimizing the lateral displacement of the support structure. Full article

Based on FLAC3D finite element analysis and field measurements, this paper studies the synchronous excavation of the deep foundation pit and the adjacent underground channel in the 17th section of the Beijing Metro Line 10 Phase II project. Due to the very tight schedule and deadline, an underground channel has been added between the double-arch tunnel and the deep foundation pit and excavated synchronously with the deep foundation pit. The minimum distance between the two excavations is 5 m. It was found that (1) the underground channel excavation destroys the intact structure of the soil around the channel and foundation pit on a larger scale, which affects the formation of soil arch behind the retaining pile and thus increases the lateral pile displacement, and the addition of anchor cables at the north and south sides of the foundation pit is not necessary; (2) if conditions permit, it is the safest to excavate the underground channel first and then the foundation pit; (3) the primary interaction spacing between the two adjacent excavations is the same depth as that of the foundation pit, and when the spacing increases to twice the depth of the foundation pit, there is basically no interaction; (4) compared with the solid and heavy soil, the adjacent existing underground channel is like a “hollow, elastic, light” tube and more sensitive to the foundation pit excavation, whose uplift and deformation rebound could exert a force on the surrounding soil and then enlarge the lateral displacement of the retaining pile. Full article

Isolation piles are critical for mitigating excavation-induced tunnel displacements, yet two unresolved challenges persist in tunnel engineering: (1) controversies regarding the influence of key parameters (e.g., pile head depth, pile length, and pile-to-pit distance) on their performance, and (2) insufficient understanding of the effects on both horizontal and vertical displacement control of tunnel. These challenges stem from the current research focus on isolated displacement components or simplified scenarios, which fails to address the complex interactions between key parameters and the deformation mechanisms. To address these gaps, this study proposes a hybrid validation framework integrating a three-dimensional finite element model (HS-Small constitutive model) with field monitoring data. A concept of “control efficiency” is introduced to quantify the effectiveness of isolation piles, complemented by a parametric sensitivity analysis framework. By synergizing the mirror image method and statistical theory, the research reveals a dual-path control mechanism involving displacement blocking and tunnel geometric reconfiguration. The findings advance the state of the art by resolving controversies over critical parameters and establishing a unified theoretical framework for coupled displacement control, providing actionable insights for optimizing isolation pile design in engineering practice. Full article

When a tunnel crosses a landslide orthogonally, this interaction can easily lead to instability in both the landslide and tunnel structures. Based on the relative positional relationship between a landslide and a tunnel, we studied the stress mode and deformation characteristics of the tunnel in three positional relationships: within the landslide mass, the sliding surface, and the sliding bed. The tunnel is a typical type located on a sliding surface at an engineering site, so we established a numerical model showing the intersection of the tunnel and the sliding surface. The plastic zone distribution, stress characteristics, and displacement distribution characteristics of the surrounding rock before and after tunnel excavation were studied. Based on the simulation results, we analyzed the control effect of anti-slide piles in controlling the tunnel’s deformation in the surrounding rock from four perspectives: the arrangement of anti-slide piles, the spacing between piles and tunnels, the diameter of anti-slide piles, and the depth of piles embedded in the bedrock. By analyzing the deformation law of the landslide mass and the force characteristics of the tunnel structure under the orthogonal conditions of a tunnel landslide, we provide theoretical guidance for the adoption of anti-slide piles to control instability in tunnel structures. Full article

The Kerr foundation model simulates the interaction between piles and soil. Considering the impact of lateral soil displacement on adjacent piles, the lateral displacement and bending moment of the adjacent piles caused by shield tunnel excavation are calculated in detail. Additionally, the reactions of groups of piles are obtained by focusing on the shielding effect of the piles on the soil displacement caused by shield tunnel excavation. The validity of the solutions is verified by comparing the calculated results with the boundary element program GEPAN. Additionally, adjacent pile lateral displacement and bending moment are compared, with and without considering lateral soil effects. Furthermore, this study investigates the influence of various factors, such as soil spring stiffness, pile–tunnel distance, ground loss ratio, and pile diameter on the pile group’s lateral displacement and bending moment. The research findings indicate that increasing the soil spring stiffness or the horizontal distance between the pile and tunnel can reduce the lateral displacement and the bending moment of the pile. On the other hand, as the ground loss ratio gradually increases, the pile lateral displacement and bending moment will also increase. However, when the diameter of the pile grows, the lateral displacement reduces, while the bending moment increases. Full article

The seismic response of structures can have a significant impact on adjacent structures’ response. Although several numerical studies have been applied in the field of tunnel–soil–pile interaction systems, there is a lack of experimental research specifically focused on the effects of this interaction on tunnel cross-section deformation and the existence of structure on encircling soil response. In this study, shaking table tests were conducted to examine the seismic response of a tunnel and the surrounding soil when an eight-story structure with piles was located in the vicinity of the tunnel. Four series of physical models were analyzed, including free-field soil (S), tunnel–soil (TS), soil-piled structure (SP), and tunnel–soil-piled structure (TSP), under sinusoidal vibration at three frequencies on loose sand. According to the results, the tunnel significantly impacts the surrounding soil response during seismic excitation with reduced acceleration at the tunnel invert and increased acceleration at the tunnel crown. In the TSP model, applied frequency affects the recorded acceleration amplitude at the tunnel invert. Although acceleration amplitude decreases at 3 Hz frequency excitation compared to the free field model, 8 Hz excitation resulted in bigger values in tunnel invert. Displacements are higher at the tunnel crown, indicating tunnel-induced soil deformation and maximum shear strain concentrated near the tunnel crown. The tunnel cross-section exhibited oval shape changes, with higher forces on the tunnel crown in the presence of piles. Full article

Due to its high section use rate and minimal environmental impact, pipe jacking technology is frequently utilized in the building of urban rail transit and other municipal projects. This paper develops a three-dimensional numerical model for the gradual construction of rectangular pipe jacking based on the quasi-rectangular pipe jacking metro station project on Shanghai Line 14 and examines the interaction between the subsequent construction of double line pipe jacking and pile foundation. To analyze the deformation pattern of the tunnel section and the ground surface during the construction period and to confirm the applicability and accuracy of the model, the simulation results are compared with the monitoring data. The findings demonstrate that although the bending moment of the pipe jacking section is distributed as a “butterfly” under the influence of the viaduct piles, the maximum positive and negative bending moments as well as the lateral and vertical radial deformations of the pipe section cross-section are all somewhat diminished. The ground surface settlement curve in the vicinity of the bearing platform exhibits a more pronounced non-uniform settlement when the two pipe jackings pass through the pile foundation in close proximity, one after the other. The largest horizontal displacement of the pile foundation is found inside the jacking pipe tunnel at a depth of roughly 17 m below ground, where pipe jacking II has a greater influence on the lateral displacement of the pile foundation than pipe jacking I. The study’s findings line up with the monitoring data, which can serve as a guide and aid in the development of initiatives of a similar nature. Full article

The underground hole pile excavation method causes a large vertical displacement in a weak stratum, which affects the safety of structures. For the first time, the hole pile excavation method is being used to construct a subway station in South China, and the settlement law of the area is not clear. It is important to clarify the deformation law of the hole pile excavation method in weak strata and the effect achieved by appropriate reinforcement measures. In this paper, by establishing a three-dimensional finite element model of the structure–soil contact element and combining it with the field monitoring data, the law of surface settlement caused by the hole pile excavation method with different thicknesses of the weak stratum has been studied. In order to improve the stability of the surrounding rock and reduce the vertical deformation of the surface, the Metro Jet System (MJS) is used to form inclined piles in the area of large surface deformation, and the effect after reinforcement was evaluated. The results show that as the weak layer thickness ratio increases, the surface settlement also increases. In the case of no reinforcement, a vertical settlement of 116 mm can be achieved when the thickness of the weak layer is 14 m. The vault of the tunnel is in the weak layer and the deformation is obvious. When the vault is not in the weak layer, the settlement is obviously reduced. After MJS pile reinforcement, under the action of soil extrusion, the self-stability of the surrounding rock is strengthened, and the oblique jet grouted pile forms a stable ‘triangle’. The vertical settlement value is basically stable at around 30 mm, which meets the requirements of the regulations. If the tunnel is not reinforced, the self-stability of the surrounding rock above the tunnel arch is poor and the maximum settlement is at the surface. After MJS reinforcement, the maximum settlement is at the vault. The vertical settlement of the ground surface can be effectively controlled by using the MJS pile forming technology in the middle of the tunnel pile driving method. Full article

The conventional support forms of foundation pit retaining piles include single-row piles, double-row piles, anchor-row piles, and so on. The double-row pile supporting structure is widely used in the deep foundation pit supporting the engineering of wharves, bridges, subways, tunnels, and high-rise and super-high-rise buildings. This study on double-row pile supporting structures mainly focuses on four aspects: (1) The influence of dimension parameters, such as pile diameter and pile length, and engineering parameters, such as pile spacing and row spacing, on the deformation control of a double-row pile structure and the stability control of foundation pits; (2) Influence of the soil arch effect on the stress and deformation of the double-row pile supporting structure; (3) Study on the deformation characteristics and rules of the components and the whole structure of the double-row pile supporting structure; (4) Study on the calculation model of pile-soil interactions. Based on the above four aspects, this paper summarizes the latest research status of the existing double-row pile supporting structure and its stress and deformation characteristics. The deformation characteristics and calculation model of the pile-soil interaction of double-row piles are reviewed and evaluated. Finally, the problems and deficiencies in the research on double-row pile support are summarized. These results provide a reference for future research on the double-row pile supporting structure of the foundation pit and the numerical analysis and calculation model and lay a solid foundation for further development of the theory. Full article

Tunneling, especially in urban areas, affects many structures on the ground, which directly influences the usability and stability of the structures. The settlement of and axial stress on the pile foundation are important factors that determine the behavioral characteristics of the pile foundation. Therefore, this study uses numerical analysis and machine learning to derive a prediction model of pile axial stress due to tunnel excavation adjacent to the piled raft. Numerical analysis data were utilized for machine learning purposes, and the effects of the input data on the prediction model were scrutinized. The numerical analysis revealed that the change in the pile axial stress resulting from tunnel excavation differed depending on the pile’s location, with the greatest axial stress reduction occurring in the center of the piled raft. Furthermore, the rate of reduction was higher in soils with lower relative densities. Several algorithms were employed to derive the prediction model, with tree-based algorithms displaying notable performance in predicting pile axial stress. Additionally, preprocessing the data with appropriate feature engineering techniques exhibited superior predictive power, and incorporating settlement data aided in enhancing the prediction model’s performance. Full article